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REVENUE REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
REVENUE REVENUE (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 202,672	$ 197,057	$ 184,101	$ 181,035	$ 160,954	$ 171,494	$ 152,773	$ 132,515	$ 764,865	$ 617,736	$ 384,402
Contract Asset	4,800								4,800			$ 1,900
Contract Liability	$ 400								400
Revenue recognized from prior period									700
Mortgage Products
Disaggregation of Revenue [Line Items]
Revenue									242,175	275,910	219,991
Credit Cards
Disaggregation of Revenue [Line Items]
Revenue									165,776	147,028	39,434
Personal Loans
Disaggregation of Revenue [Line Items]
Revenue									134,199	88,244	66,457
Other Products And Services
Disaggregation of Revenue [Line Items]
Revenue									222,715	106,554	58,520
Non-mortgage Products
Disaggregation of Revenue [Line Items]
Revenue									$ 522,690	$ 341,826	$ 164,411